Frames 17 and 19; Butts

September 9, 2014   Hours spent building to date:  103

Back to the boring stuff — done with frames 17 and 19.  They are toward the aft end of the pilothouse above the fuel tanks.

I have been very wasteful of my plywood, cutting everything I can from full sheets for strength, but producing a lot of big offcuts.  Mindful of the fact that I wasted a sheet with my mistake at 8.33 and wanting to have a full sheet left for a planking mistake, I decided to do frame 17 using three smaller pieces.

This means I had to connect the pieces into one big piece somehow.  There are three methods that I know of:

— Gluing together with epoxy and strengthening with biaxial fiberglass tape — a “butt joint.”

— Gluing together and bridging with another piece of plywood for strength — a “butt block.”

— Scarfing by cutting wide, shallow angles on either side of the two pieces and gluing them on top of one another to give the appearance of one piece.

Scarfing is the elegant solution, and very strong.  But it would require tricky layout — measuring for the scarf, measuring for the frame, cutting the frame, cutting the scarf, and hoping it all fits.  And no one if ever going to see these areas in the hull, so strength is what counts.

So I used a combination of one and two — a butt block on the front and tape down the backside. And in this case and areas where I had to join two full sheets, I picked areas with a lot of other structure — the keel, fore-and-aft-girders, doublers.

Should have checked this with Mark, but it sure seems strong to me.  Some of the single sheets are still a little flippy, but I think I could stand on 17 without it breaking.

Frame 17

Frame 17

Frame 19

Frame 19

Butt Block at 17 -- a girder goes into the slot on the right.

Butt Block at 17 — a girder goes into the slot on the right.

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